1. Field of the Invention
The present invention relates to a wiring board for electrical tests. By way of example, the electrical tests include the insulation and connection tests of high-density wiring in a printed-wiring circuit board, a circuit board for an integrated circuit or a circuit board for a liquid-crystal display, and the ON-resistance tests of a semiconductor device.
2. Description of the Related Art
As semiconductor devices have been subjected to increased density of integration and density of surface packaging, the tests of the devices and the packaging circuit boards thereof have become very difficult.
In the case of the semiconductor devices, several tens .about. several hundred of electrodes are laid out on silicon chips of several millimeters square. Further, a semiconductor device having more than one thousand electrodes will be developed. The tests of such devices are extremely difficult. Especially, it is difficult to test a so-called "bare chip" which is a silicon chip before being packaged (namely, before being mounted on a lead frame and encapsulated with a resin). Granted that although testing of the bare chips is possible, it is not commonly undertaken because of complicated test jigs and heavy test expenses.
On the other hand, also in the case of the wiring circuit boards for use in the packaging, the microfabrication of wiring has been promoted. It has been required of the wiring circuit boards to have wiring leads at a pitch of or below 0.1 [mm] and electrodes at a pitch of or below 0.1 [mm] (equal to the electrode pitch of the semiconductor devices). Such wiring circuit boards cannot be tested with regard to insulation and connection by a conventional method which permits the electrodes to be temporarily connected and disconnected. An example of such a method is that in which anisotropic conductive rubber is brought into pressed touch with the electrodes as disclosed in the official gazette of Japanese Patent Application Laid-open No. 3269/1984.